The infectious disease, tuberculosis (TB), is the leading cause of death worldwide from a single human pathogen, claiming more adult lives than diseases such as acquired immunodeficiency syndrome (AIDS), malaria, diarrhea, leprosy and all other tropical diseases combined (Zumla A, Grange J. B M J (1998) 316, 1962-1964). About one third of the world's population is currently infected with M. tuberculosis; 10% of those infected will develop clinical diseases, particularly those who also have the human immunodeficiency virus (HIV) infection (Zumla A, Grange J. B M J (1998) 316, 1962-1964). With the discovery of effective anti-mycobacterial agents (including ethambutol, isoniazid, pyrazinamide, rifampicin and streptomycin) and a reduction in poverty, there was a drastic decline in the number of TB cases, especially in developed nations. However, since the late 1980s, the number of cases of TB throughout the world has been increasing rapidly partly due to the emergence of multi-drug resistant M. tuberculosis (C. E. Barry, III, Biochemical Pharmacology (1997) 54, 1165-1172). According to the World Health Organization (World Health Organization. 1993 92. per Besra G S, Brennan P J. 1997. J Pharm Pharmacol 49 (Suppl. 1):25-30.s), it is expected that the annual death rate caused by TB will reach an overwhelming 3.5 million by the year 2000.
Thus, the TB problem requires urgent attention. Short course anti-TB regiments initially using at least three first-line drugs (including isoniazid, rifampicin and pyrazinamide) are often not effective due to an increase in the number of tuberculosis strains that have become resistant to current drugs. For example the World Health Organization (WHO) recently reported that the death rate of patients with multi-drug resistant (MDR) tuberculosis in the US was approximately 70%. Current treatment is also very expensive: a 3 drugs regimen is needed (more than $500/month cost per patient). Thus the major problems faced in tuberculosis control are poor infrastructures for diagnosis and drug supply. The failure of patients to complete therapy as well as inappropriate monotherapy has led to the emergence and distribution of strains of Mycobacterium tuberculosis resistant to every available chemotherapy (Bloom B R and Murray C J L, Science (1992) 257, 1055-1064). Such organisms will not remain confined to the Third World or to the poor and indigent of developed countries. The recent documentation of the spread of a single clone of multi-drug-resistant Mycobacterium tuberculosis (the “W” strain) throughout the continental United States and Europe highlights the danger of an airborne pathogen in our global society (Bifani P J, et al., JAMA (1996) 275, 452-457).
Consequently, there is a need for an anti-mycobacteria drug for humans and non-humans which are effective against human and non-human mycobacteria.